In general, biological, chemical, and/or optical analysis of sample fluids is used in analyzing blood clinically collected from a patient and diagnosing diseases, as well as a chemical field and a biotechnology field. Various kinds of chip structures have been developed and used so as to provide an analyzing and/or diagnosing apparatus, which has a further smaller size, and performs analysis of sample fluid in more effective manner. As such, the object of development of a lab-on-a-chip is to make it possible for various functions to be performed in one chip so as to increase effectiveness in analysis and/or diagnosis of diseases, and to make it possible to manufacture a rapid kit.
A lab-on-a-chip means implementing various test processes, which are performed in a laboratory, for example, the separation, refinement, mixing, labeling, analysis, and washing, etc. of a sample, on a chip having a small size. Techniques related to microfluidics and a micro-LHS are typically used in designing the lab-on-a-chip. Also, in manufacturing a chip-structure implementing microfluidics and the micro-LHS, a chip, in which a microchannel is formed at the interior of the chip by using a semiconductor circuit designing technique, has been put on the market.
In general, detecting and analyzing analytes in a very small amount, which are included in sample fluid, such as blood, a body fluid, urine, etc., includes analyzing if a sample fluid reacts against proteins, such as antigens, antibodies, etc. or other material, which have been previously immobilized on a chip, while moving through a channel having a pipe-shaped structure formed in the interior of the chip, through detection of fluorescent material, etc. Therefore, a technique for observing movement of fluids moving in a chip having a channel through the channel and a technique for manufacturing a channel structure are the most important core techniques in manufacturing a small-sized chip for performing fluid analysis and obtaining accurate analysis result by using such a chip.
In a chip (or structure) having a microchannel implementing microfluidics, in order to allow fluids to flow through an inner space formed by a microchannel, a small-size motor is used, or a method for limiting the width and height of a channel so as to allow fluids to move through a microchannel due to capillary phenomenon is used. At this time, in a chip where main driving force causing movement of fluids is capillary force, the result of investigation shows that fact that fluids flowing in a space formed by a channel have an irregular and nonuniform movement pattern. It is understood that such a phenomenon occurs because acting force due to relative action between upper and lower inner walls of a channel and fluids is different from acting force due to relative action between left and lower inner walls of the channel and fluids. As a result, such a nonuniform movement pattern of fluids has been a big obstacle to detection and analysis of analytes in a very small amount in the fluids.
Meanwhile, a chip, which has a sample inlet and a sample outlet included at both ends thereof and has a structure where fluids injected into the sample inlet is discharged through the sample outlet through a closed channel shaped similar to a pipe, is manufactured in such a manner that upper and lower substrates are manufactured and are assembled with each other. However, in order to manufacture a microchannel structure having a size below several tens of micrometers, it is difficult to process edge parts of a channel without loss of other part thereof, and it is also difficult to control standards and quality of a product in mass production. Also, the fine difference of such a channel structure obstructs uniform flux of fluids so that it causes a sample analysis result without consistency in a chip used in detecting analytes in an extremely small amount from a small amount of a sample.
For example, a chip shown in FIGS. 1 and 2 is one example of a conventional chip. The chip includes a body 10 formed in such a manner that a first substrate 11 and a second substrate 12 are assembled with each other. A channel recess 13b having a predetermined width and depth is formed at the first substrate 11. In order to form a space to be filled with a sample, the channel recess 13b is formed at the first substrate 11 in such a manner that it extends in a longitudinal direction of the substrate while having a predetermined width and a predetermined depth. Therefore, when the first substrate 11 and the second substrate 12 are assembled with each other, the channel 13 has an airtight space. Also, a sample inlet 14, which extends to the outside of the channel so as to allow a sample to be injected into the channel 13, is formed at one end of the channel 13, and a sample outlet 15, which extends to the outside of the channel so as to allow the sample to be discharged, is formed at the other end of the channel. When sample fluid to be analyzed is injected into the channel 13, the injected sample fluid moves along the channel 13 toward the sample outlet 15. As shown in FIG. 3, when the sample fluid forms a pattern while moving, a difference of relative actions between the fluid, which passes though the channel, and upper, lower, left, and right inner walls 13a of the channel can cause a difference of capillary force, which is main driving force of movement of fluid in the microchannel. As a result, irregular pattern where a pattern is firstly formed along the left and right inner walls 13a is generated. Accordingly, many bubbles are generated in the fluid, thereby causing many problems in analyzing the sample fluid.
In a chip having a channel, which has a space for allowing fluids to flow and also has a sample inlet formed at one side of the channel and a sample outlet formed at the other side thereof, the inventors manufactured a chip having an expanding part, which has a sectional area larger than sectional areas of the left and right inner walls of the channel, formed at entire or a part of each left and right inner wall, and analyzed a pattern of movement of fluids. As a result, the inventors confirmed that the shape of movement of the fluids passing through the channel has a very regular and uniform pattern in the chip according to the present invention so that they completed the present invention.